Opposition to President Obama’s rumored nomination of former Nebraska senator Chuck Hagel as secretary of defense is growing into widespread backlash. Hagel has come under fire for voting against imposing unilateral sanctions against Iran; for suggesting that since the “genie of nuclear weapons is already out of the bottle,” it doesn’t matter so much what Iran does; and for asserting that “the Jewish lobby” exerts undue influence on Capitol Hill.

Although the battle over the prospective nominee is becoming increasingly bitter, sources say that, if nominated, Hagel will sail through the Senate hearings. A former Pentagon official tells National Review Online that Hagel “would make it through the Senate confirmation process without a whole lot of difficulty.” According to a source familiar with the confirmation process, once a nomination is announced, scrutiny of the nominee’s views is standard procedure: “There have been many people who have views that concern the members,” NRO’s source says, and it’s likely that we will look back on today’s dispute as “a tempest in a teapot.”

Nonetheless, criticism of the reported frontrunner for the Pentagon’s top spot continues to mount. In a matter of weeks, opposition to his nomination has whipped from pro-Israel groups to the editorial page of the Washington Post and now to cable TV, where this anti-Hagel ad is warning viewers about Hagel’s vote against imposing unilateral sanctions against Iran. Having taken a body blow with Susan Rice removing herself from the nomination process for secretary of state, the administration is now at risk of suffering a second.

Focus is also turning to the former Senator’s views on Cuba. “He’s been abysmal on Cuba” says Florida congressman Mario Diaz-Balart, who notes that opposition to Hagel’s rumored nomination is already beginning to mount in the Cuban-American community. “Senator Hagel has been a very well known apologist for the Castro atrocities for years,” he adds. “If there’s one thing Senator Hagel has been consistent on, he’s been consistent on appeasing the enemies of the United States, like Iran and Cuba.”

Hagel has been a vocal opponent of the embargo against Cuba, calling American policy toward the Castro regime “outdated” and “irrelevant.” He also advocated returning six-year-old Elián González, who fled Cuba on a raft with his mother, back to the island after he arrived safely in America.

Florida senator Marco Rubio’s office said in a statement earlier today, “Promoting democracy in Latin America is a priority for Sen. Rubio, and he’s put holds on other administration nominees over the issue. I’m sure we would have questions about Cuba positions.”

Given the dynamics of Washington, D.C., defeating Hagel may require his opponents — including National Review’s editors — to cause an uproar that makes the administration reconsider his nomination altogether. And the longer the administration waits to make an announcement, sources say, the more likely that is. “In Washington, D.C.,” says the former Pentagon official, “you can get nibbled to death by a thousand ducks. So, from an administration point of view, if you believe this is the guy and you can get him through, you should announce him.”

But the slew of attacks on Hagel is also rousing his defenders.

“Hagel’s position on Iran has been glibly mischaracterized,” says Andrew Parasiliti, who served as Hagel’s foreign-policy adviser from 2001 to 2005, and is now editor of Al-Monitor. “He gets the nature of the threat from Iran and has not taken the use of force off the table. He also knows the use of force can have its own unforeseen consequences. Look at Iraq and Afghanistan. Clearly sanctions alone have not halted Iran’s nuclear progress. Both the Bush and Obama administrations have done diplomacy with Iran. We need to use all levers of influence. Hagel is right where you would want any responsible statesman to be on this issue.”

The Obama administration itself is also responding to the attacks. According to an administration official, Hagel would “walk into the Pentagon and command immediate respect based just on his résumé.” He adds that “the attacks on him as somehow anti-Israel are patently unfair.”

Former Hagel staffers are circulating a flyer on Capitol Hill in order to clarify his positions on Iran, Hamas, Hezbollah, and the wider Middle East, and former secretary of defense William Cohen is also circling the wagons, along with former national security advisers Brent Scowcroft and Zbigniew Brzezinski.

Former Pentagon officials have conflicting views about how Hagel would fare leading the Department of Defense. “One of the things we are still struggling with,” says Robert Andrews, a former special assistant to the secretary of the Army, “is to put fine strokes on what our threat is. Hagel’s view would not be to see terrorist movements as threats. He wants to negotiate everything. He’s the wrong guy for the job.” Another former Pentagon official, however, says that, while Hagel’s views “could be troublesome,” they may change if he becomes secretary of defense. “Once you get into a position like that,” he says, “your views sometimes change based on your responsibilities and what you see.”

Whatever the case, the opposition forces have gotten their message through to the White House. In the coming weeks, we will discover whether they have succeeded in swaying the president.